Most animals, even the domesticated ones, and many people harbor intestinal parasites which are sometimes detrimental to health and well being. Many of these intestinal parasites produce microscopic eggs or ova which become mixed with feces. The discovery and identification of worm ova in feces is essential to the diagnosis of certain parasite infestations in man and animals. The examination of feces is commonly and frequently performed in most medical laboratories and in veterinary hospitals.
There are a number of methods and techniques of discovery and identifying parasite eggs in feces. These methods have gradually evolved from the direct examination of a fecal smear on a microscope slide. Concentration techniques using centrifugation or floatation increased test efficiency and improved the accuracy of the determination.
A prior method is to mix a bit of feces and a drop of water on microscope slide to be examined at 100 power magnification. While this method is rapid and easily completed, eggs and oocysts are not concentrated. The number of eggs is small and if the technician is not extremely conscientious, the diagnosis may easily be missed.
A concentration technique includes thoroughly mixing the feces with a flotation liquid, such as sugar water, by stirring with a wooden applicator stick. The higher specific gravity of the fluid causes the eggs to float to the surface where they can be collected on a microscope slide. As the eggs float to the surface to reach the slide on the surface of the liquid, they can be harvested for examination with the microscope. Debris such as grass and other roughage obstruct the eggs from reaching the surface and impedence to ova recovery seriously effects test efficiency and accuracy. This concern is significant with animals eating a substantial amount of roughage. Early efforts to remove extraneous matter and clumps of feces from the flotation solution including pouring the mixture through cheese cloth or wire mesh. This system was unpleasant and posed potential contamination of the premises as well as the operator.
More recently, Robert J. Greenwald in U.S. Pat. No. 3,819,045 described a fecal analyzer utilizing a perforated plate equipped with a plunger which is inserted in a cup containing the fecal/liquid suspension. The perforated plate is equipped with holes of a diameter in the range of "well above 0.5 millimeter" and "well below 1.5 millimeter" while indicating that holes of 1 millimeter are particularly suitable. The use of the Greenwald apparatus is an improvement over the straining method, but still requires substantial handling by the operator. As the strainer is pushed into the mixing chamber, debris is forced to the bottom of the container but splash back is frequent and contamination is a common occurance. This device has been marketed under the trademark "FECALYZER" by EVSCO Pharmaceutical Corp.
In U.S. Pat. No. 3,936,373, A. D. Studer describes another device directed to the test. In this device a filter thimble is inserted into the cup containing the fecal/fluid mixture. Holes in the range of 1.0 to 1.5 millimeter are provided in the thimble with the holes spaced apart about 1.5 millimeter. This provides for about 20% flow-through area if the surface were at right angles to the flow direction. The vast majority of the holes are in the vertical wall of the timble thus severely reducing the flow area through which the ova must pass to reach the surface of the liquid and the microscope slide. A device similar to that described in the Studer Patent is marketed under the trademark "OVASSAY" by Pitman-Moore, Inc. utilizing a cone-shaped strainer with essentially horizontal apertures over the entire sloped surface of the cone. This commercial device provides essentially no vertical passageways through which the ova can easily pass.
Control tests using these devices indicate that the screen systems can prevent fifty to seventy-five percent or even all of the ova from reaching the microscope slide, that would otherwise have reached the surface. For some "hard to test" ova the screens can prevent all of the ova from reaching the screen, particularly for shorter test periods. Although these devices have allegedly reduced the interference and impedence by fecal matter, the imposition of a screen appear to impede the flow of the ova to an even greater degree.
In order to satisfy the above limitations, the following objects and aims are provided:
It is an object of my invention to provide a fecal analyzer with increased test efficiency and improved accuracy.
It is a further object of this invention to provide a fecal analyzer that requires minimal handling of the feces and the liquid suspension of the feces and allows the operator to collect the ova without significant contamination of either the laboratory or the operator.
It is a particular object of this invention to provide a fecal analyzer that is particularly effective for domesticated pets and humans and those animals that do not consume a substantial amount of grass or other roughage and yet provide a separation barrier between the feces and the ova collection point.
It is a particular object of this invention to provide a separation device that will prevent large clumps of feces from reaching the ova collection point but that will basically allow the ova to rise essentially unimpeded through the screen device.
It is a further object of this invention to provide a method of handling a feces sample and collection of the ova possibly intrained in the feces without any significant chance of contamination of either the premises or the operator by material carried in the feces matter.
These and other objects, while not satisfied by the above prior art, will become apparent through the reading of the balance of the specification.